Thanks for your suggestion. I search through web, most of the article discussion about cakephp and CodeIgniter. And in terms of speed CodeIgniter is best.
Take a look at symfony and yii framework. Both definitely worth trying. http://www.symfony-project.org/ http://www.yiiframework.com/
There's actually a small discussion of this going on right now at reddit: http://www.reddit.com/r/PHP/comments/d0cvb/need_help_php_enterprise_framework/
Thanks for your suggestion.. Finally I decided to take codeIgniter.. In future I will use some other framework..
I've used Zend before, haven't used CodeIgniter or CakePHP but their also popular - so you might want to check out all 3 to see which coding 'style' is for you.